Publication number | US20060093076 A1 |

Publication type | Application |

Application number | US 11/259,688 |

Publication date | May 4, 2006 |

Filing date | Oct 26, 2005 |

Priority date | Oct 29, 2004 |

Publication number | 11259688, 259688, US 2006/0093076 A1, US 2006/093076 A1, US 20060093076 A1, US 20060093076A1, US 2006093076 A1, US 2006093076A1, US-A1-20060093076, US-A1-2006093076, US2006/0093076A1, US2006/093076A1, US20060093076 A1, US20060093076A1, US2006093076 A1, US2006093076A1 |

Inventors | Jae-Yong Lee, Yun-Sang Park, Bong-Gee Song |

Original Assignee | Samsung Electronics Co., Ltd. |

Export Citation | BiBTeX, EndNote, RefMan |

Referenced by (10), Classifications (12), Legal Events (1) | |

External Links: USPTO, USPTO Assignment, Espacenet | |

US 20060093076 A1

Abstract

An apparatus and method for estimating a frequency offset using a preamble signal having a periodically repeated structure. According to the apparatus and method, the sum of or the difference between an input signal and a delay signal is calculated without obtaining a simple correlation value between the input signal and the delay signal, and then a correlation value between a calculated signal and the delay signal is obtained. Accordingly, the implementation complexity of the circuit and the power consumption are reduced, and thus, the battery cycle of a terminal provided with the frequency offset estimating circuit can be increased.

Claims(12)

a delay unit for delaying an input signal;

a calculation unit for calculating one of a sum of and a difference between the input signal and a delay signal;

a correlator for correlating a conjugate of a calculated signal with a conjugate of the delay signal and providing correlation values;

a moving sum unit for summing output values of the correlator;

a detector for detecting a specified point at which the correlation value becomes maximum; and

a frequency offset calculator for estimating the frequency offset by calculating a phase change of a present signal against the delay signal at the specified point.

a first delay unit for delaying the input signal for a period of repeated patterns and providing a first delay signal; and

a second delay unit for delaying the first delay signal from the first delay unit for the period of the repeated patterns and providing a second delay signal.

an adder for calculating a sum of the input signal and the second delay signal from the second delay unit; and

a subtracter for calculating a difference between the input signal and the second delay signal from the second delay.

a first correlator for correlating an output of the adder with a conjugate of the delay signal; and

a second correlator for correlating an output of the subtracter with the conjugate of the delay signal.

a first moving sum unit for accumulating an output of the first correlator for the period of the repeated patterns to output an accumulated signal; and

a second moving sum unit for accumulating an output of the second correlator for the period of the repeated patterns to output an accumulated signal.

where C[n] denotes the delay signal having an imaginary value and S[n] denotes the present signal.

delaying an input signal;

calculating one of a sum of and a difference between the input signal and a delay signal;

correlating a conjugate of a calculated signal with a conjugate of the delay signal;

providing correlation values;

performing a moving sum of the correlation values;

detecting a specified point at which the correlation value becomes maximum; and

estimating the frequency offset by calculating a phase change of a present signal against the delay signal at the specified point.

a first delaying step of delaying the input signal for a period of a repeated patterns;

providing a first delay signal;

a second delaying step of delaying the first delay signal for the period of the repeated patterns; and

providing a second delay signal.

calculating a sum of the input signal and the second delay signal; and

calculating a difference between the input signal and the second delay signal.

correlating an added signal with a conjugate of the delay signal; and

correlating an subtracted signal with the conjugate of the delay signal.

performing the moving sum of the first correlation signal for the period of the repeated patterns to output an accumulated signal; and

performing the moving sum of the second correlation signal for the period of the repeated patterns to output an accumulated signal.

where C[n] denotes the delay signal having an imaginary value and S[n] denotes the present signal.

Description

This application claims priority to an application entitled “Apparatus for Estimating Frequency Offset in Communication System and Method Thereof” filed in the Korean Industrial Property Office on Oct. 29, 2004 and assigned Serial No. 2004-87312, the contents of which are hereby incorporated by reference.

1. Field of the Invention

The present invention relates generally to an apparatus for estimating a frequency offset in a receiver and a method thereof, which obtains synchronization using periodically repeated signal patterns.

2. Description of the Related Art

In a communication system, a transmitter transmits a sync signal to a receiver, and the receiver performs synchronization (or sync) using the sync signal. Recently, for a high-rate data transmission, a communication system using an OFDMA (Orthogonal Frequency Division Multiple Access) system has been proposed in the IEEE 802.16 committee. According to this IEEE 802.16 Standard, in the OFDMA type communication system, a transmitter transmits a preamble pattern to a receiver, and the receiver acquires the start of a frame, i.e., the frame sync, from the received preamble pattern.

**10** has repeated patterns **11**, **12**, and **13**. In the two successive periods of such repeated patterns, for example, the receiver delays a signal of an ‘A’ period, correlates the delay signal of the ‘A’ period with a signal of a ‘B’ period, and sums the two signals. If the ‘A’ period signal and the ‘B’ period signal have the same pattern, their summed value maximizes. Because the repeated patterns **11**, **12**, and **13** have three periods, the correlation value between the repeated pattern **11** of the ‘A’ period and the repeated pattern **12** of the ‘B’ period and the correlation value between the repeated pattern **12** of the ‘B’ period and the repeated pattern **13** of the ‘C’ period should be accumulatively summed. Accordingly, if the respective signal period has m samples, **2** *m *samples should be accumulatively summed. Further, if the same signals are repeated, a start point of a frame can be found by detecting the signal period in that the summed correlation value maximizes, and in the same manner, the frame sync can also be extracted.

A frequency offset occurs because of an oscillator error between the transmitter and the receiver. A conventional frequency offset estimating apparatus estimates the frequency offset by obtaining a phase difference between the presently received signal and the previously received delay signal, and provides the estimated frequency offset to the oscillator.

**1** in the section D is equal to the signal at the second point P**2** in the section E, the frequency offset can be estimated by comparing the signal at the point P**1** with the signal at the point P**2** and obtaining the phase difference between them. This frequency offset is used to obtain the coincidence of the transmitted and received frequencies.

In summary, in order to estimate the phase difference of the same signal, the repeated patterns of the preamble pattern should be detected. Generally, a frequency offset estimating apparatus determines the point where the frequency offset will be obtained in the received signal according to the correlation values for obtaining the start position of the frame. That is, as illustrated in

As described above, according to the conventional frequency offset estimating apparatus, the repeated patterns **11**, **12**, and **13** have three signal periods, have three signal periods, and thus, if the respective signal period has m samples, 2m samples should accumulatively be summed. Consequently, this summing operation increases the circuit complexity and power consumption.

Accordingly, the present invention has been designed to solve the above and other problems occurring in the prior art. An object of the present invention is to provide an apparatus and method for estimating a frequency offset that reduces the implementation complexity and power consumption in obtaining the frequency offset.

In order to accomplish the above and other objects, according to the apparatus and method for estimating a frequency offset, a frame sync can be obtained in a manner that the sum of or the difference between an input signal and a delay signal is calculated, without obtaining a simple correlation value between the input signal and the delay signal, and then a correlation value between a calculated signal and the delay signal is obtained.

In accordance with one aspect of the present invention, there is provided an apparatus for estimating a frequency offset. The apparatus includes a delay unit for delaying an input signal, a calculation unit for calculating a sum of or a difference between the input signal and a delay signal, a correlator for correlating a conjugate of a calculated signal with a conjugate of the delay signal and providing correlation values, a moving sum unit for summing output values of the correlator, a detector for detecting a specified point at which the correlation value becomes maximum, and a frequency offset calculator for estimating the frequency offset by calculating a phase change of a present signal against the delay signal at the specified point.

In accordance with another aspect of the present invention, there is provided a method for estimating a frequency offset. The method includes the steps of delaying an input signal, calculating a sum of or a difference between the input signal and a delay signal, correlating a conjugate of a calculated signal with a conjugate of the delay signal and providing correlation values, performing a moving sum of the correlation values, detecting a specified point at which the correlation value becomes maximum, and estimating the frequency offset by calculating a phase change of a present signal against the delay signal at the specified point.

The above and other objects, features, and advantages of the present invention will be more apparent from the following detailed description taken in conjunction with the accompanying drawings, in which:

Preferred embodiments of the present invention will be described in detail hereinafter with reference to the accompanying drawings. In the following description of the present invention, the same drawing reference numerals are used for the same elements even in different drawings. Although a number of specific features, such as an element, the number of pixels, a specified numeric key, etc., are given below, they are presented for a better understanding of the present invention only. Also, it will be clear to those skilled in the art that the present invention can easily be practiced without such specific features or through their modifications.

Additionally, a detailed description of known functions and configurations incorporated herein will be omitted when it may obscure the subject matter of the present invention.

The present invention detects an initial sync, i.e., a start position of a frame, in a system that uses a periodically repeated preamble pattern to obtain a frame sync. Accordingly, a transmitter constructs and transmits a preamble as illustrated in

In the embodiment of the present invention, the complexity of the receiver can be reduced by reducing the sections in which the moving sums are obtained using the characteristic of the repeated patterns. Accordingly, in the embodiment of the present invention, the sums of the repeated sections are obtained, and the correlation value thereof is obtained. More specifically, the receiver obtains the correlation of the preamble as expressed by Equation (1) in order to detect the start of the frame.

In Equation (1), r[k] denotes a k-th received signal sample, and r*[k] denotes a complex-conjugated value of r[k]. In this case, if n=0 and no noise exists, the correlation value can be divided into two sections, that is, a section from k=o to k=m−1 and a section from k=m to k=2m−1, as expressed by Equation (2).

Here, if the section from k=m to k=2m−b **1** is changed to the section from k=0 to k=m−1 with respect to the correlation value

of the section, the correlation value is changed to

Accordingly, referring to **2**(B) and the period **1**(A) becomes

and the correlation value between the conjugated period **3**(C) and the period **2**(B) becomes

The correlation value that the receiver intends to obtain becomes Correlation(B,A)+Correlation(C,B). Here, because the r[k] has a period of m samples and the preamble pattern has the repeated patterns, the correlation value can be arranged as shown in Equation (3).

Here, if the frequency offset exists, the signal delayed for m samples is compared with the present sample to cause a specified phase change, which is expressed by Equation (4).

*r[k−m]=r[k]e* ^{jΘ}

*r[k+m]=r[k]e* ^{−jΘ} (4)

Meanwhile, the correlation value obtained using Equations (2) and (3) is expressed by Equation (5).

The frequency shift Θ given as above has a relation as shown in Equation (6) with the frequency offset.

In Equation (6), N is an FFT point number, and N/3 is given to the equation because the construction of _{COR}, the phase shift Θ can be obtained as expressed by

The Accordingly, the estimated frequency offset is expressed by Equation (8).

The frequency offset value obtained as above is used to control an oscillator through a loop filter.

**102**, a conjugator **104**, a first correlator **110**, a first Z^{−2m }moving sum unit **112**, a first magnitude calculator **114**, a second correlator **120**, a second Z^{−2m }moving sum unit **122**, a second magnitude calculator **124**, an ñ detector **130**, and a frequency offset calculator **140**.

If a signal is input to the frequency offset estimating apparatus **100**, the input signal is provided to the delay unit **102** and the conjugator **104**. The delay unit **102** delays the input signal for a period corresponding to m samples. Accordingly, the delay unit **102** delays the input signal r[n+k] by m samples, and outputs a signal r[n+k−m] to the second correlator **110**. The conjugator **104** conjugates the input signal r[n+k] and outputs the conjugated signal to the first correlator **110**. The first correlator **110** has an input part connected to an output part of the delay unit **102** and an output part of the conjugator **104**.

The first correlator **110** correlates the output signal of the delay unit **102** and the output signal of the conjugator **104**, and outputs a correlation value to the first Z^{−2m }moving sum unit **112**. The first Z^{−2m }moving sum unit **112** sums the correlation values output from the first correlator **110**, and in particular, performs an accumulative summing of 2m samples.

As described above, because the repeated patterns have three periods, the correlation value between the repeated pattern of the first period and the repeated pattern of the second period and the correlation value between the repeated pattern of the second period and the repeated pattern of the third period should accumulatively be summed. More specifically, if the respective signal period includes m samples, the first Z^{−2m }moving sum unit **112** accumulatively sums 2m samples and the summed value to the frequency offset calculator **140** and the first magnitude calculator **114**. The output of the first Z^{−2m }moving sum unit **112** has a complex value including an imaginary value and a real value, and the frequency offset calculator **140** can calculate the frequency offset from the output signal of the first Z^{−2m }moving sum unit **112**.

Additionally, in order to acquire the sync of the frame, the output signal of the first Z^{−2m }moving sum unit **112** is provided to the first magnitude calculator **114**. The first magnitude calculator **114** calculates the magnitude of the output signal of the first Z^{−2m }moving sum unit **112** and outputs the calculated signal to the ñ detector **130**.

The second correlator **120** receives the signal input from the frequency offset estimating apparatus **100** and the output signal of the conjugator **104**. In this case, the second correlator **120** correlates the input signal with the output signal of the conjugator **104**, and outputs the correlation value to the second Z^{−2m }moving sum unit **122**. The second Z^{−2m }moving sum unit **122** accumulatively sums the correlation value output from the second correlator **120** for a period of 2m samples and outputs the summed value to the second magnitude calculator **124**. The second magnitude calculator **124** has an input part connected to the output part of the second Z^{−2m }moving sum unit **122**, and if the output signal of the second Z^{−2m }moving sum unit **122** is provided, it calculates the magnitude of the output signal to output the calculated signal to the ñ detector **130**.

The ñ detector **130** detects the point ñ at which the magnitude of the correlation value of the repeated patterns maximizes on the basis of the magnitude of the correlation value of the specified section of the presently input signal and the magnitude of the correlation value of the specified section of the delay signal. The ñ detector **130** outputs the detected point ñ to the frequency offset calculator **140**. The frequency offset calculator **140** calculates the frequency offset from the correlation value of the ñ point among the correlation values output from the first Z^{−2m }moving sum unit **112**.

In the conventional frequency offset estimating apparatus as described above, the first Z^{−2m }moving sum unit **112**, for example, accumulatively sums the correlation value between the repeated pattern of the first period A **11** and the repeated pattern of the second period B **12** and the correlation value between the repeated pattern of the second period B **12** and the repeated pattern of the third period C **13**. Therefore, if the respective signal period includes m samples, it accumulatively sums the correlation values from the first correlator **110** for a period of 2m samples.

The present invention reduces the complexity of the conventional frequency offset estimating apparatus that should accumulatively sum the correlation values for a period of 2m samples. More specifically, in the embodiment of the present invention, the complexity of the receiver is reduced by reducing the section in which the moving sum is obtained using the characteristic of the repeated patterns. For this, in the embodiment of the present invention, the sum of or the difference between the input signal and the delay signal of the repeated section is obtained and then the correlation value thereof is obtained. Because the preamble signal has the same repeated sections **11**, **12**, and **13**, the sum of or the difference between the input signal and the delay signal is calculated instead of obtaining the simple correlation value between the input signal and the delay signal. Thereafter, the correlation value between the calculated signal and the delay signal is obtained.

More specifically, in the present invention, the sum of or the difference between the input signal of the frequency offset estimating apparatus and the delay signal thereof is calculated when ‘K[n]’ input to the ñ detector and ‘C[n]’ input to the frequency offset calculator are obtained.

In order to explain the construction of the present invention, ‘K[n]’ and ‘C[n]’ are expressed in Equation (9) below.

Additionally, by arranging Equation (9) using the relation of Equation (4), Equation (10) can be obtained. As shown in Equation (10), the newly obtained value K is a real number and the value C is given as an imaginary number.

In Equation (10), the value C[n] may be calculated in a modified form such as r[k−m]−r[m+k] within the scope of the present invention. According to Equation (9), the frequency offset can be given as shown in Equation (11).

More specifically, C[n] does not have a complex value but has an imaginary value, and K[n] does not have a complex value but has a real value. This means that the ñ detector requires only the magnitude value of the signal and the frequency offset calculator requires only the phase value in the frequency offset estimating apparatus. Accordingly, in the present invention, the frequency offset calculator calculates the phase change of the signal, and it does not use the real value, i.e., the magnitude value.

**30**, a K[n] calculating unit **32**, a C[n] calculating unit **34**, an ñ detector **36**, and a frequency offset calculator **38**. The S[n] calculating unit **30** correlates the input signal and its conjugated signal for a specified section and outputs S[n].

The K[n] calculating unit **32** delays the input signal, calculates the sum of a delay signal and the input signal for a specified section, and then correlates the calculated signal with the delay signal to output K[n]. The C[n] calculating unit **34** delays the input signal, calculates the sum of a delay signal and the input signal for a specified section, and correlates the calculated signal with the delay signal to output C[n]. As described above, C[n] includes the imaginary value only.

The output part of the S[n] calculating unit **30** and the output part of the K[n] calculating unit are connected to the input part of the ñ detector **36**. The ñ detector **36** detects the point ñ at which the magnitude of the correlation value of the repeated patterns becomes maximum. The ñ detector **36** divides the magnitude of the correlation value of the specified section of the delay signal by the magnitude of the correlation value of the specified section of the present input signal, and determines the point at which the quotient becomes maximum as the point ñ. More specifically, the ñ detector **36** searches for the ñ value that maximizes D(n)=K(n)/S(n), and outputs the ñ value and S[n] to the frequency offset calculator **38**. The frequency offset calculator **38** calculates the phase change of the signal, and thus does not use the real value of the signal, i.e., the magnitude value. The frequency offset calculator **38** calculates the phase change of S[n] that is the present signal corresponding to the delay signal C[n] at the point ñ according to the output from the ñ detector **36** using Equation (11).

**200** of **256** and a frequency offset calculator **258**.

Referring to **200** includes a conjugator **248**, a correlator **250**, a Z^{−2m }moving sum unit **252**, and a magnitude calculator **254**. The frequency offset estimating apparatus **200** further includes a first delay unit **202**, a conjugator **206**, a second delay unit **204**, an adder **214**, a subtracter **216**, a real-number correlator **210**, an imaginary-number correlator **212**, a first Z^{−m }moving sum unit **218**, and a second Z^{−m }moving sum unit **219**.

The first delay unit **202** delays the input signal for a period corresponding to m samples. Accordingly, the first delay unit **202** delays the input signal r[n+k] by m samples, and outputs a signal r[n+k−m]. The conjugator **206** conjugates the signal r[n+k−m] and outputs the conjugated signal to the real-number correlator **210** and the imaginary-number correlator **212**. The second delay unit **204** delays the signal r[n+k−m] output from the first delay unit **202** for a period corresponding to m samples, and outputs a signal r[n+k−2m] to the adder **214** and the subtracter **216**. The input signal r[n+k] and the signal r[n+k−2m] output from the second delay unit **204** are input to the adder **214** and the subtracter **216**.

The adder **214** adds the input signal and the signal from the second delay unit **204**, and outputs a signal of a real-number value to the real-number correlator **210**. The subtracter **216** subtracts the signal from the second delay unit **204** from the input signal, and outputs a signal of an imaginary-number value to the correlator **212**.

The real-number correlator **210** correlates the signal of the real number provided from the adder **214** with the conjugated value r*[n+k−m] of r[n+k−m] output from the conjugator **206**, and outputs the correlation value of the real number to the second Z^{−m }moving sum unit **219**. The second Z^{−m }moving sum unit **219** receives the correlation value of the real number from the real-number correlator **212** and performs the summing of m samples.

The frequency offset estimating apparatus according to the present invention further includes the ñ detector **256** and the frequency offset calculator **258**. The ñ detector **256** receives S[n] from the magnitude calculator **254** and K[n] from the second Z^{−m }moving sum unit **219**. The ñ detector **256** detects the point ñ at which the magnitude of the correlation value of the repeated patterns becomes maximum, and thus it does not use the imaginary-number value of the signal, i.e., the phase value. More specifically, the ñ detector **256** determines the point at which the quotient obtained by dividing the magnitude K[n] of the correlation value of the specified section of the delay signal by the magnitude S[n] of the correlation value of the specified section of the present input signal becomes maximum as the point ñ. That is, the ñ detector **256** searches for the ñ value that maximizes D(n)=K(n)/S(n), and outputs the results to the frequency offset calculator **258**.

The imaginary-number correlator **212** correlates the signal of the imaginary number provided from the subtracter **216** with the conjugated value r*[n+k−m] of r[n+k−m] output from the conjugator **206**, and outputs the correlation value of the imaginary number to the first Z^{−m }moving sum unit **218**. The first Z^{−m }moving sum unit **218** receives the correlation value of the imaginary number from the imaginary-number correlator **212** and sums m samples to provide the resultant value to the frequency offset calculator **258**. The frequency offset calculator **258** calculates the phase change of the signal, and thus does not use the real value of the signal, i.e., the magnitude value.

The frequency offset calculator **258** calculates the phase change of S[n] that is the present signal with respect to the delay signal C[n] at the point ñ according to the output from the ñ detector **256** using Equation (1).

In ^{−m }moving sum units **218** and **219** are provided in the frequency offset estimating apparatus, but they correspond to one complex-number Z^{−m }moving sum unit in practice. Accordingly, the actual complexity is greatly reduced in comparison to the Z^{−m }moving sum unit of the conventional frequency offset estimating apparatus. Additionally, the two complex-number multipliers, i.e., the two correlators **210** and **212**, in

The reference signs ‘Re’ and ‘Im’ in the respective correlators **201** and **212** in

The features of the frequency offset estimating apparatus according to the present invention in comparison to those of the conventional frequency offset estimating apparatus are shown in Table 1 below.

TABLE 1 | |||

Present | |||

Classification | Prior Art | Invention | Remarks |

Conjugate | Two | Two | * Both are of a complex |

type, and I and Q mean | |||

the respective numbers | |||

of bits. | |||

Delay | m | 2 m | * m = [2048/3] = 683 |

Element | (802.16 OFDMA) | ||

(12 bits) | |||

Add/Subtract | Two | * Adders/subtracters | |

used in the moving sum | |||

adders are excluded. | |||

Multiply | 12 × 12 bits | One Real | Same as one complex- |

Value One | number multiply | ||

Imaginary | |||

Value | |||

Moving | 2 m (24 bits) | m (25 bits) | The present invention |

Sum | can reduce the number of | ||

delay elements having | |||

a large number of bits. | |||

As shown in Table 1, the frequency offset estimating apparatus according to the present invention can reduce the complexity of the receiver by reducing the section in which the moving sum unit obtains the moving sums in comparison to the conventional frequency offset estimating apparatus.

**202** and **204** of the frequency offset estimating apparatus according the present invention delay the signal for a period corresponding to m samples in step **310**. In this case, m may be the number of samples included in the repeated period. The adder **212** and the subtracter **214** of the frequency offset estimating apparatus calculate the sum of and the difference between the delay signal and the presently input signal in step **320**. The correlators **210** and **212** correlate the conjugates of the calculated signal and the delay signal, and the first and second moving sum units **218** and **219** sum the correlation signals from the correlators **210** and **212** for m repeated periods in step **340**. The first Z^{−m }moving sum unit **218** receives the correlation value of the imaginary number from the correlator **212** and performs a moving sum of m samples. The second Z^{−m }moving sum unit **219** receives the correlation value of the real number from the correlator **210** and performs a moving sum of m samples.

The frequency offset calculator **258** of the frequency offset estimating apparatus calculates the phase change of the present signal with respect to the delay signal at the point ñ according to the output from the ñ detector **256** using Equation (11) in step **350**.

In order to obtain an accurate estimation of the frequency offset, the timing sync should accurately be matched. The timing sync is for the ñ detector to accurately search for the point at which the correlation value maximizes, which is not included in the present invention. In order to estimate the timing sync more accurately, it may be required to repeatedly perform the estimation or to permit a slight offset at the position in which the maximum value is estimated in some cases.

In the embodiment of the present invention as described above, the value ñ, when the value K is greatest, is searched for and the frequency offset is estimated using the value C[n] at that time. Because the parts for obtaining the magnitude value S[n] have the same complexity, they are excluded from the comparison in Table 1. As shown in Table 1, the number of 25-bit delay elements can be reduced as many as m(=682 in the case of 802.16) through the present invention.

Additionally, in the embodiments as described above, the circuit of obtaining S[n] is only exemplary and can be replaced by other circuits for obtaining the magnitude value of the signal.

Additionally, to take the imaginary value and the real value in the embodiment of the present invention is to minimize the complexity of the circuit. It is also possible to extract the magnitude information about the entire complex value.

As described above, according to the present invention, the sums of the repeated sections are obtained and then the correlation values thereof are obtained. Accordingly, the section in which the moving sum is obtained is reduced, and thus the complexity of the receiver can be reduced.

In the embodiments of the present invention, the frequency offset estimating apparatus is applied to the OFDMA type frame sync extraction of the 802.16 standard. However, the present invention can also be applied to other systems for achieving the frame sync by delay and correlation using repeated preamble patterns.

From the foregoing, it will be apparent that the present invention has the advantages that its circuit construction is simplified with low power consumption by reducing the implementation complexity of the frequency offset estimating apparatus. Accordingly, the battery cycle of a terminal provided with the frequency offset estimating circuit can be increased.

While the present invention has been shown and described with reference to certain preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present invention as defined by the appended claims.

Referenced by

Citing Patent | Filing date | Publication date | Applicant | Title |
---|---|---|---|---|

US7711074 * | Aug 31, 2005 | May 4, 2010 | Samsung Electronics Co., Ltd. | Sync extraction apparatus in communication system and method thereof |

US7885319 * | Sep 10, 2007 | Feb 8, 2011 | Broadcom Corporation | Multiple branch PSYNC detection module |

US7912137 | Jan 10, 2007 | Mar 22, 2011 | Amicus Wireless Technology Ltd. | OFDMA device and method of correcting frequency offset in OFDMA signals |

US8054920 * | Dec 12, 2007 | Nov 8, 2011 | Harris Corporation | Communications device and related method with improved acquisition estimates of frequency offset and phase error |

US8059766 * | Dec 12, 2007 | Nov 15, 2011 | Harris Corporation | Communications device and related method with reduced false detects during start of message bit correlation |

US8059767 * | Dec 12, 2007 | Nov 15, 2011 | Harris Corporation | Communications device and related method that detects symbol timing |

US8296344 * | Jun 16, 2008 | Oct 23, 2012 | Comtech Ef Data Corp. | Time delay and frequency offset calculation system and related methods |

US8433011 * | Jan 27, 2011 | Apr 30, 2013 | Fujitsu Semiconductor Limited | Signal processing device, method and receiving device |

US20090037503 * | Jun 16, 2008 | Feb 5, 2009 | Lianfeng Peng | Time delay and frequency offset calculation system and related methods |

US20110188610 * | Aug 4, 2011 | Fujitsu Semiconductor Limited | Signal processing device, method and receiving device |

Classifications

U.S. Classification | 375/343, 375/346 |

International Classification | H04L27/06, H03D1/04 |

Cooperative Classification | H04L27/2684, H04L27/2656, H04L27/2613, H04L27/2675, H04L27/2657, H03J2200/02 |

European Classification | H04L27/26M5C3, H04L27/26M1R |

Legal Events

Date | Code | Event | Description |
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Oct 26, 2005 | AS | Assignment | Owner name: SAMSUNG ELECTRONICS CO., LTD., KOREA, REPUBLIC OF Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:LEE, JAE-YONG;PARK, YUN-SANG;SONG, BONG-GEE;REEL/FRAME:017153/0364 Effective date: 20051024 |

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